edited by Heather Fry, Steve Ketteridge and Stephanie Marshall
Routledge, 2009
Buku Referensi
edited by George A. Hawkins
McGraw-Hill, 1968
Buku Teks
cordinating editor, Geoge A. Hawkins
McGraw-Hill, 1968
Buku Teks
Mortimore, Tilly
Whurr Publishers, 2006
Buku Teks
Griffith, H. Winter
Fisher Books, 1998
Buku Teks